My beardie does this all the time. I'm not an expert, but I'll tell you how I interpret it. It depends what else she's doing when she sticks out her tounge.
If she licks something: she's curious
If she is basking: she's opening her mouth to help release excess heat
If she's puffed up or even hissing: she's really stressed out, especially if she's eyeing someone while she does this
My guess is that it's that last one, since your beardie is in a new environment. Check the thread about enclosures to make sure that the habitat is suited to his or her needs. A few questions come to mind. Is it large enough? Is there a hot side and a cool side? Is the hot side within your beardie's needed temperature range? Also, is there a lot of movement or noise in your house? You may want to provide an older beardie a place to hide, though I don't recommend this for younger ones. I've heard that sometimes the juveniles will hide so much they don't eat.
Hope this helps!